When the going gets tough, the tough get going...without underwear. If you're Bradley Cooper, that is.

During a Monday appearance on The Ellen DeGeneres Show, the American Hustle star admitted to facing a bit of a wardrobe challenge prior to attending the White House State Dinner last week.

"I'm prepping for this new movie and I'm trying to gain weight fast, so I've gained about 15 pounds in four weeks and nothing fits me anymore," the 39-year-old actor explained. "So I wore the tuxedo I wore to the Golden Globes. I just sort of threw it in the bag and brought it and went to Washington D.C. and then I'm getting dressed like 10 minutes before I was supposed go, and literally the pants go up to like here," he said, gesturing to his upper thighs. "And I just started laughing, like, 'This is hilarious, I'm going to meet the president.'"

"I had to go commando...because there was no room at all. I did. I had to," Cooper admitted. "And you're sitting there and it's a lot of getting up [to greet people]. You know what I mean? And I couldn't stand up really."

He added, "It was a nightmare. But I made it through."

It was on Tuesday, Feb. 11, that Cooper and girlfriend Suki Waterhouse made their way to the formal event, held in honor of visiting French President Francois Hollande.

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